This invention relates to the condensing and depositing of ammonium chloride contained in gaseous process streams. In one of its aspects this invention relates more particularly to hydrocarbon hydrodesulfurization, hydrodenitrogenation, hydrocracking, and reforming processes. In still another of its aspects this invention relates to a process in which ammonium chloride is present in a gaseous stream that must be subjected to gas compression with prevention of depositing of the ammonium chloride in the gas-compressing zone.
This invention is of particular interest in hydrodesulfurization processes in which hydrocarbon stock is passed along with hydrogen into a catalytic hydrodesulfurization zone in which they are contacted with a catalyst, usually a cobalt-molybdenum or nickel-molybdenum on alumina support catalyst, at a temperature and pressure sufficient to produce desulfurized hydrocarbons, hydrogen, and other gases. It is well known that, usually, among the products in a hydrodesulfurization effluent stream are ammonium chloride or ammonium chloride-forming constituents. On passing any part of the gaseous effluent stream containing ammonium chloride or ammonium chloride-forming constituents through a compressing zone there is a risk of problems with depositing of ammonium chloride on the equipment in the compressing zone. In turbine compressors, deposits of a solid ammonium chloride on the blades of the compressor can unbalance the blades and necessitate expensive shutdown. In reciprocating compressors the valve ports can become plugged, again necessitating expensive shutdown of the operation.
Various methods have been proposed for eliminating the depositing. These methods usually entail the removal of ammonium chloride or ammonium chloride-forming constituents from the process streams. As an example, U.S. Pat. No. 2,929,772 contacts the gas streams with an adsorbent or an absorbent upstream of the gas-compressing zone to remove the ammonium chloride or ammonium chloride-forming components. Other processes reduce the temperature to induce depositing in a zone from which the deposits can easily be washed prior to passing any portion of the reforming process effluent through a compression zone. Both of these methods require fairly expensive equipment which may leave a sufficient amount of material in the gas stream to allow troublesome deposits. The method of this invention provides relatively inexpensive means to prevent deposition within a given portion of the process such as a compression zone. The method is particularly effective when used along with means for removing at least some of the ammonium chloride or ammonium chloride-forming constituents.
It is therefore an object of this invention to provide a method for preventing depositing of ammonium chloride from a gaseous stream containing ammonium chloride or ammonium chloride-forming constituents. It is another object of this invention to prevent the deposition of ammonium chloride in the compression zone for hydrogen recycle in a catalytic hydrodesulfurization process.
Other aspects, objects, and the various advantages of this invention will become apparent upon study of this specification, the drawing, and the appended claims.